Chain saw antipinch guard arm

ABSTRACT

An antipinch guard arm for chain saw blades comprises a stiff, strong arm and pivotal mounting means mounting one end of the arm on the saw in a plane parallel to the plane of the saw blade. The arm is pivotal between a first position, downwardly divergent from the blade, a second position substantially parallel and adjacent to the blade, and a third position, upwardly divergent from the blade. At the beginning of the saw operation, the blade is placed on one side of a log or other object to be sawn and the arm in its downwardly divergent position on the opposite side. The free end of the arm is braced against the ground or other support. The chain saw then is applied to the log in the usual manner. As the cut progresses, the blade moves in the direction of the arm, which supports the object from the opposite side and thus prevents pinching. At the conclusion of the cut, the arm lies in its second position immediately adjacent the blade, where it protects the saw chain from damage by contacting the ground. When desired, the saw may be shifted to the third position, where it serves as an auxiliary handle when felling and limbing.

Patent Lam 1 51 Tim. 5

[54] CHAIN SAW ANTIPINCH GUARD AM [72] Inventor: Donald D. Lanz, Route2, Box 155,

Oregon City, Oreg. 97045 [22] Filed: Dec. 12,1969

[21] Appl.No.: 884,456

Primary ExaminerDonald R. Schran Attorney-Eugene D. Farley 57] ABSTRACTAn antipinch guard arm for chain saw blades comprises a stiff, strongarm and pivotal mounting means mounting one end of the arm on the saw ina plane parallel to the plane of the saw blade. The arm is pivotalbetween a first position, downwardly divergent from the blade, a secondposition substantially parallel and adjacent to the blade, and a thirdposition, upwardly divergent from the blade. At the beginning of the sawoperation, the blade is placed on one side ofa log or other object to besawn and the arm in its downwardly divergent position on the oppositeside. The free end of the arm is braced against the ground or othersupport. The chain saw then is applied to the log in the usual manner.As the cut progresses, the blade moves in the direction of the arm,which supports the object from the opposite side and thus preventspinching. At the conclusion of the cut, the arm lies in its secondposition immediately adjacent the blade, where it protects the saw chainfrom damage by contacting the ground. When desired, the saw may beshifted to the third position, where it serves as an auxiliary handlewhen felling and limbing.

7 Claims, 3 Drawing Figures CHAIN SAW ANTIPINCH GUARD ARM This inventionrelates to a guard arm which, when attached to a chain saw, preventspinching of the blade during operation of the saw and prevents damage tothe saw chain from rocks and dirt at the conclusion of each saw out.

A problem commonly encountered in the use of chain saws in that ofpinching. As the cut progresses, the log collapses against the blade andbinds the saw chain.

When bucking of large diameter this problem may be corrected by drivinga wedge in the kerf. However, wedges may not be used when bucking logsof small diameter, because of interference of the wedge with the sawchain.

A second common problem attending the use of chain saws is that ofdulling the saw chain. Where the log or other object being sawn rests onor near the ground, the blade of the saw is prone to drop downwardly atthe conclusion of each cut. The free-running saw chain thereupon engagesthe underlying dirt and rocks. This obviously dulls the chain so that itmust be resharpened frequently.

It accordingly is the object of the present invention to pro vide aguard arm for use as an attachment on chain saws, and having thefollowing advantages:

It eliminates pinching by providing lifting leverage directly under thesaw cut.

It protects the saw chain by preventing it from plunging into dirt androcks below the log after each cut is completed.

It provides a prybar for prying a log off the ground and placing it inworking position preliminary to sawing it into lengths.

It makes possible cutting at the end of the saw bar by providing a newleverage point between the end of the guard arm and the saw handle.

It protects the operator of the saw against accidental leg cuts.

It provides a secondary handle for use during falling and limbing oftrees.

It is easily applied to chain saws of commercial types without extensivemodification of their structure.

It is easily mounted and demounted, and easily adjusted between itsvarious use positions.

The manner in which the foregoing and other objects of the presentinvention are accomplished will be apparent from the accompanyingspecification and claims, considered together with the drawings wherein:

FIG. 1 is a view in side elevation of a chain saw equipped with theherein described guard; and

FIGS. 2 and 3 are fragmentary, detail views taken along lines 22 of FIG.1 and 3-3 of FIG. 2, respectively.

As illustrated in the drawings, the herein described antipinch guard armis applicable to conventional chain saws including a case housing themotor assembly; an operating handle 12 and a peripheral handle 14 bymeans of which the saw is held; a forwardly directed case extension 16;a bucking plate 18 bolted to the latter; an outwardly and forwardlydirected saw blade 20 coupled to the motor through suitable connections;and a saw chain 22 mounted on the blade.

The guard arm comprises an arm 24 of strong structural material such asbar steel. lt preferably has a length equal to, or slightly longer than,the length of saw blade 20. Preferably it is concavely arcuate at itsouter extremity to conform to the curvature of the outer end of the sawblade. A foot or bearing pad 26 is attached to its outer end.

Pivotal mounting means are providing for mounting the arm on the saw andfor permitting free angular movement of the arm with reference to thesaw blade.

In the illustrated form of the invention, the pivotal mounting meansincludes a shaft 28 extending outwardly from the saw blade substantiallynormal thereto. The shaft is mounted at the base of the saw blade,adjacent its lower margin, by suitable attaching means. Thus it may bethreaded or riveted into dogging plate W, or, if a dogging plate is notpresent in the saw assembly, into a sidewall ofcase extension 16.

Journaled on shaft 28 are a pair of arm support brackets 30, 32. Bracket30 comprises a straight, stiff bar, while bracket 32 comprises a doublybent bar. This provides an offset point of attachment of bracket 32 toshaft 28.

The inner ends of brackets 30, 32journal shaft 26. This may beaccomplished simply by providing in the respective ends of the bracketsopenings which receive the shaft.

The outer ends of brackets 30, 32 extend substantially parallel to eachother in spaced relation and receive between them the inner end of bar24. The bar and brackets are suitably locked together, preferably byproviding a series of aligned perforations through all three members.These receive bolts 36 which permit longitudinal adjustment of bar 24 asrequired to provide the desired arm length.

The arm assembly thus constituted is releasably secured on shaft 28 bymeans of a clip 38. This comprises a U-shaped member having through itsopposite sides openings dimensioned to receive the shaft. A cuppedextension 40 clips releasably about peripheral handle 14.

A coil spring 42 is interposed between clip 38 and bracket 32. The forceof the spring resiliently presses the arm assembly, and specifically theoutside face of bracket member 30 thereof, against a structural memberof the saw. This may be either case extension 16, or dogging plate 18.

The pivotal mounting provided in this manner permits free angularmovement of arm 24 about shaft 28. Stop means are provided for arrestingthis movement inpositions predetermined to establish operation of thearm in the desired manner.

One such stop means comprises a bolt 44 or other projecting membersecured in the side face of case extension 16, or dogging plate 18.

Stop 44 is located in a position such that it is engaged by the arm whenthe arm is in its downwardly divergent position. A second stop 46 isengaged by the arm when the arm is in its saw chain-guarding position,i.e., substantially aligned with the working stretch ofsaw chain 22.

A third stop 48 similarly is attached to a side face of case extension]6, or of dogging plate 18. However, it is positioned nearly at the topof these elements in a location such that it engages and locks the armagainst the saw case with the arm in its elevated position.

Adjustment of the arm between these three positions is accomplishedmerely by moving it outwardly with respect to the saw blade against thepressure of spring 42. When this is done, the arm may be shiftedlaterally along shaft 28 a distance sufficient to permit it to clear thestops as it is swung to the desired angular position. Upon releasing thearm, it is pressed inwardly by the action of spring 42, whereupon it isretained in its new operative position by the action of the selectedstop.

OPERATION In the application of the saw chain attachment to the buckingof a log 50, arm 24 is adjusted to its downward divergent position andinserted beneath the log, with foot 26 bearing against the ground orother support. Blade 20 is placed above the log, the log levered to aworking position, and the saw cut started.

Operating the chain saw in the usual manner, by dogging the log withplate 18 and levering blade 20 downwardly, has the effect of applyingthe pressure of arm 24 to the underside of the log directly opposite thecut. This prevents pinching of the saw blade.

At the completion of the cut, the arm engages stop 46. This places thearm in its guarding position adjacent the blade, where it guards the sawchain from damage by dirt and rocks.

When it is desired to elevate arm 24, as when limbing and felling, thearm is displaced laterally until it clears stops 46, 48. It then iselevated and released. Thereupon it is retained in its elevatedposition, wedged against the: saw case, by stop 48. In this position itmay be used as a third handle, ifdesired.

In this manner there is provided an attachment universally applicable tocommercial chain saws which not only effectively prevents pinching ofthe saw while cutting, and guards the chain against damage by contactwith dirt and rocks, but which also is useful as a prybar and as anauxiliary handle.

Having thus described my invention in preferred embodiments, I claim:

I. In combination with a chain saw having an outwardly projecting sawchain blade mounting a saw chain having a working stretch, an antipitchguard attachment comprising:

a. a stiff arm of substantial strength,

b. pivotal mounting means mounting one end of the arm on the sawadjacent the base of the blade in a plane substantially parallel to theplane of the blade,

0. the arm being pivotal, as the saw is applied to an object being sawn,between an initial angular position wherein it extends divergently tothe working stretch of the saw chain in a position in bearing engagementwith the side of the object opposite said working stretch, and a secondangular position wherein it is adjacent and substantially aligned withthe blade for protecting from damage the working stretch of the sawchain, and

d. stop means on the saw positioned for stopping the angular movement ofthe arm at said second position,

e. the outer free end of the arm being arranged for bearing engagementwith a support, thereby enabling the application to the object beingsawn of supporting pressure in a location opposite the saw cut.

2-. The attachment of claim 1 wherein the arm is at least substantiallyas long as the saw blade and is provided at its outer end with a footfor bearing engagement with a support.

3. The attachment of claim 3 wherein the arm comprises a bar receivedbetween a pair of support brackets, and securing means securing the barbetween the brackets in a predetermined degree of extension.

4. The attachment of claim 1 wherein the pivotal mounting meanscomprises a shaft mounted on the saw and extending outwardlysubstantially normal to the plane of the blade, the inner end of the armbeing mounted on the shaft for pivotal and longitudinal movementrelative thereto for releasable engagement of the arm with the stopmeans.

jecting saw chain blade, an antipitch guard attachment comprising:

a. a stiff arm of substantial strength,

b. pivotal mounting means mounting one end of the arm on the sawadjacent the base of the blade in a plane substantially parallel to theplane of the blade, the pivotal mounting means comprising a shaftmounted on the saw and extending outwardly substantially normal to theplane of the blade, the inner end of the arm being journaled on theshaft, and spring clip means on the end of the shaft releasablyretaining the arm thereon and exerting resilient pressure laterallyagainst the arm, thereby holding in operative position against the saw,the arm being pivotal, as the saw is applied to an object being sawn,between an initial angular position wherein it extends divergently tothe blade in a position in bearing engagement with the side of theobject opposite the saw blade, and the second angular position whereinit is adjacent and substantially aligned with the blade,

d. the outer free end of the arm being arranged for bearing engagementwith a support, thereby enabling the application to the object beingsawn of supporting pressure in a location opposite the saw cut.

1. In combination with a chain saw having an outwardly projecting sawchain blade mounting a saw chain having a working stretch, an antipitchguard attachment comprising: a. a stiff arm of substantial strength, b.pivotal mounting means mounting one end of the arm on the saw adjacentthe base of the blade in a plane substantially parallel to the plane ofthe blade, c. the arm being pivotal, as the saw is applied to an objectbeing sawn, between an initial angular position wherein it extendsdivergently to the working stretch of the saw chain in a position inbearing engagement with the side of the object opposite said workingstretch, and a second angular position wherein it is adjacent andsubstantially aligned with the blade for protecting from damage theworking stretch of the saw chain, and d. stop means on the sawpositioned for stopping the angular movement of the arm at said secondposition, e. the outer free end of the arm being arranged for bearingengagement with a support, thereby enabling the application to theobject being sawn of supporting pressure in a location opposite the sawcut.
 2. The attachment of claim 1 wherein the arm is at leastsubstantially as long as the saw blade and is provided at its outer endwith a foot for bearing engagement with a support.
 3. The attachment ofclaim 1 wherein the arm comprises a bar received between a pair ofsupport brackets, and securing means securing the bar between thebrackets in a predetermined degree of extension.
 4. The attachment ofclaim 1 wherein the pivotal mounting means comprises a shaft mounted onthe saw and extending outwardly substantially normal to the plane of theblade, the inner end of the arm being mounted on the shaft for pivotaland longitudinal movement relative thereto for releasable engagement ofthe arm with the stop means.
 5. The attachment of claim 4 includingspring clip means on the end of the shaft releasably retaining the armthereon and exerting resilient pressure laterally against said arm,thereby holding it in operative position against the saw.
 6. Theattachment of claim 1 including stop means on the saw positioned forengaging the arm and maintaining it in an elevated rest position to theside of the blaDe opposite the working stretch of the saw chain.
 7. Incombination with a chain saw having an outwardly projecting saw chainblade, an antipitch guard attachment comprising: a. a stiff arm ofsubstantial strength, b. pivotal mounting means mounting one end of thearm on the saw adjacent the base of the blade in a plane substantiallyparallel to the plane of the blade, the pivotal mounting meanscomprising a shaft mounted on the saw and extending outwardlysubstantially normal to the plane of the blade, the inner end of the armbeing journaled on the shaft, and spring clip means on the end of theshaft releasably retaining the arm thereon and exerting resilientpressure laterally against the arm, thereby holding in operativeposition against the saw, c. the arm being pivotal, as the saw isapplied to an object being sawn, between an initial angular positionwherein it extends divergently to the blade in a position in bearingengagement with the side of the object opposite the saw blade, and thesecond angular position wherein it is adjacent and substantially alignedwith the blade, d. the outer free end of the arm being arranged forbearing engagement with a support, thereby enabling the application tothe object being sawn of supporting pressure in a location opposite thesaw cut.